The ultimate objective of the proposed research is to advance understanding of mechanics of ventricular contraction in terms of strain distribution over the free and septal walls of the ventricles as well as in global parameters such as transmural pressure, volume and shape of the ventricle. Indispensable for the goal is a method to document instantaneous ventricular wall geometry. We propose to establish such a method by using biplane high-speed cineradiography with multiple markers implanted in the subendocardium and epicardium of the canine ventricle. Our pilot studies indicate that (1) 40 steel balls (1.5 mm in diameter) can be implanted in the endo- and epicardial layers of the ventricular walls in an intact dog and (2) their image can be captured on X-ray films and their coordinates in space can be recovered with an average error of 0.1 mm. The proposed studies include establishing (1) an optimal number and distribution of the markers in the left and right ventricular walls in a close association with (2) an algorithm for reconstructing endo-and epi-cardial surfaces from the marker coordinates and (3) estimating ventricular lumen volume with an error range of 10% or less. We also aim at developing a system for automatic capturing of the marker images and digitizing the coordinates on paired X-ray films. With the proposed method established, we will be able to initiate a new series of rigorous analyses of regional abnormalities of ventricular wall and their impact on global parameters of ventricular contraction. However, the scope of the present proposal is restricted to establishing the use and limitation of the multiple marker cineradiography.